Model train control system



Nov 30, 1965 D. J. LESLIE MODEL TRAIN CONTROL SYSTEM 4 Sheets-Sheet 1Filed Dec. 3, 1962 E L m n M w 4 m 0 ZV m 1% firaen/srs.

Nov. 30, 1965 D. J. LESLIE 3,220,356

MODEL TRAIN CONTROL SYSTEM Filed Dec. 3, 1962 4 Sheets-Sheet 2 INVENTOR.

Don/4L0 J 1594/5 6 N 4! Z In, irraeA/sys.

NOV. 1965 n. J. LESLIE MODEL TRAIN CONTROL SYSTEM 4 Sheets-Sheet 4 FiledDec. 5, 1962 E m R./ E w m 1J United States Patent 3,220,356 MODEL TRAINCONTROL SYSTEM Donald J. Leslie, 267 S. Fair Oaks Ave., Pasadena, Calif.Filed Dec. 3, 1962, Ser. No. 242,579 16 Claims. (Cl. 104-151) Thisapplication is a continuation-in-part of my prior application Serial No.145,349, filed October 16, 1961, now abandoned, and entitled Model TrainControl System. This invention relates to a control system for aplurality of model or toy trains operating on the same track, andparticularly to a system wherein each train may be separately controlledas to direction as well as speed.

Patents to Ozanne and Mostek, No. 1,778,465 and 2,754,432 suggest use ofand halves of alternating current excitation for use in providingseparately adjusted power for two trains operating on the same track.Thus each half of the AC. supply is rectified and separately controlled.The respective trains are provided with rectifiers so that they respondonly to the respective halves of the A.C. supply. An object of thisinvention is to make it possible to reverse the trains individually aswell as to control their speed. Use is made of a relay for switching thefield connections or field windings, the relay sensing a critical changein the excitation appropriately to provide the requisite connections.

Another object of this invention is to provide a system of thischaracter that utilizes simple circuit design to accomplish effectivenon-chatter operation of the reversing relays.

Another object of this invention is to provide improved power supplysystems for use in separately controlling opposite phases of analternating current waveform.

This invention possesses many other advantages, and has other objectswhich may be made more clearly ap parent from a consideration of severalembodiments of the invention. For this purpose, there are shown a fewforms in the drawings accompanying and forming part of the presentspecification. These forms will now be described in detail, illustratingthe general principles of the invention; but it is to be understood thatthis detailed description is not to be taken in a limiting sense, sincethe scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is a diagrammatic view of a control system incorporating thepresent invention;

FIG. 2 is a diagrammatic view of a modified control system incorporatingthe present invention;

FIGS. 3, 4 and 5 are diagrammatic views illustrating modified excitationcontrol systems for use in the forms of FIG. 1 or FIG 2;

FIG. 6 is a diagrammatic view of a typical relay for use in the presentcontrol system; and

FIG. 7 is a diagrammatic view of a system similar to FIG. 1 but showingthe incorporation of means for preventing relay chatter.

In FIG. 1 there is diagrammatically illustrated at 10 and 11 powerplants of two toy or model locomotives.

The power plant 10 comprises a direct current motor, having an armature12 and a series field winding 13. The field winding 13 has a center tap14 connected to one of the armature terminals 15, as by the aid of alead 16.

The motor is adapted to be excited by one phase of an alternatingcurrent supply applied between rails 17 and 18 of the track system. Abrush or pick-up wheel 19 forming a part of the toy or model locomotivethus establishes an electrical connection to one of the rails 17. Thepick-up wheel 19 is connected to the other armature terminal 20 via aunidirectionally conductive device or rectifying diode 21. v

A switch arm 22 connects one of the two end terminals 23 or 24 of thefield winding 13 to a second brush or wheel pick-up 25 cooperating withthe other track rail 18.

Either one part or the other of the motor field winding 13 is operative,depending upon which terminal 23 or 24 is operative. The winding partsare so polarized that the direction of motor torque reverses inaccordance with the operation of the contacts 23 or 24.

The power plant for locomotive 11 is identical except that the rectifier21 is oppositely arranged wherebythe power plant responds to theopposite phase of the alternating current excitation applied to rails 17and 18.

The excitation for the rails is provided by a step down transformer 26,the primary winding 27 of which is cooperable with a commercial powersource. The secondary winding 28 is designed to deliver a voltageconsistent with the rating of the motor structures for the locomotives.

One terminal of secondary winding is grounded at 29 as is the rail 18.The other terminal of secondary winding 28 is connected to the rail 17,thus connected in parallel to the secondary winding 28 are twopotentiometer resistors 31 and 32. Sliders 33 and 34 cooperable with theresistors 31 and 32 connect respectively to two oppositely polarizedunidirectionally conductive devices or rectifying diodes 35 and 36. Thediodes 35 and 36 are joined at a terminal 37. The terminal 37 connectsto the rail 17 via two normally closed switches 38 and 39 of a reversingcircuit to be hereinafter described.

When the sliders 33 and 34 are at corresponding po sition-s along theirrespective resistors 31 and 32, the positive and negative half cycles ofthe voltage applied to the rail 17 are equal in amplitude. However, thesliders 33 and 34 are separately adjustable and, accordingly, thepositive half cycle of the supply may be of quite different amplitudefrom the negative half cycle of the supply. Since the locomotive powerplants 10 and 11 respectively sense the positive and negative halfcycles of the supply, the average voltage applied to the motors isdetermined and the speeds are accordingly separately controlled.

In order to move the switch arm 22, a latching relay structure 40 isprovided, of which the switch arm 22 forms a part. The latching relayrequires for its operation a current substantially greater than normallyprovided by the power supply. Hence, the relay is normally inactive. Themanner in which extra current for operating the relay is provided willbe hereinafter described.

While any relay of the latching type may be used, the latching relay 40disclosed herein by way of example in FIG. 6 incorporates an operatingpush rod 41 movable upwardly along a path or axis a in response to apulse of current applied to the relay coil 42. A retracting spring 43pulls the push rod 41 downwardly.

The push rod 41 is pivotally connected to the lower end of a rocker 44as by the aid of a pin 45. The rocker 44 has a lower end that engagescentering bars 46 on opposite sides of axis a underthe influence ofretracting spring 43. The centering bars cause the rocker to be alignedwith the push rod 41.

As the rocker 44 moves upwardly along line a, its upper end engages oneof two contiguous symmetrical recesses 47 or 48 formed on the surface ofthe switch arm 22 that is Opposed to the rocker 44. The switch arm 22 ispivoted on a pin 49 spaced symmetrically above the recesses 47 and 48and on the line of movement a. When the arm is in one asymmetricalangular position, the recess 47 intersects the line a. Thus, as therocker 44 advances, it enters recess 47 and moves the arm 22 to thephantom-line position, the rocker pivoting about its pin 45 in theprocess. When the rocker retracts, it passes easily along the recess 47without shifting the arm. In the phantom-line position, the oppositerecess 48 is now over center, and it will be engaged on the nextadvancement of the rocker 44. Accordingly, the arm 22 is movedalternately on succeeding pulses applied to relay coil 42.

In order to operate the latching relay 40 and provide an adequate pulseto its coil 42, a reversing circuit is interposed between the rail 17and the power supply. The reversing circuit includes a capacitor 51 thatnormally stores a charge derived from a charging battery 52. The chargestored by the capacitor 51 is adequate to operate the coil 42 of thelatching relay. In place of the battery 52 and capacitor 51, a smallpower supply could be substituted, comprising, for example, a diode inseries with an A.C. source.

One terminal 53 of capacitor 51 connects to one of two arms 54 of theswitch 38 by the aid of which the capacitor receives its charge from thebattery or passes its charge to the rail 17. The other terminal of thecapacitor is grounded. The switch arm 54 normally engages contact 55that connects with the positive terminal of the battery 52, but ismovable to engage instead a contact 56 connected by a lead 57 to theoutput terminal 58 of the reversing circuit and thence to rail 17. Inorder to move the switch arm 54, the switch 38 has an operating button59 that is normally returned by a spring 60 to a position in which thebattery contact 55 is engaged by the arm 54.

The switch 38 also operates to disconnect the power supply when thecapacitor 51 is applied to the rail 17. For this purpose, use is made ofthe second arm 61 of the switch 38. This arm 61 is connected to powersupply terminal 37 and normally engages a contact 62 that, in dependenceupon switch 39, connects to output terminal 58. Thus, contact 62 ofswitch 38 connects to a contact 63 normally engaged by an arm 64 ofswitch 39. The arm 64 is connected to the output terminal 58 of thereversing circuit and to the rail 17 The positive pulse provided bycapacitor 51 on depression of button 59 finds its way via diode 21 tolatching relay coil 42 to reverse the locomotive 10. The pulse isblocked by diode 21 and hence only the first locomotive is reversed.

In order to operate the reversing relay 40', a second condenser 51' isprovided. This condenser has a terminal 53' normally connected to thenegative terminal of a battery 52 via the second arm 54' and contact 55of switch 39. On depression of button 59', the arm 54' engages contact56' and a negative pulse is applied to latching relay 40'.

By virtue of the system just described, the direction of movement andthe speed of the toy or model locomotives operating on the same trackare therefore separately controlled.

In the form illustrated in FIG. 2, a reversing relay 70 is arranged tobe operated by a spring 71 when current in the reversing relay coil of72 drops below a critical value. In this instance, a simpler powersupply is provided for achieving this control.

Two potentiometers 31 and 32 have corresponding terminals connected toone side of a secondary winding 28 remote from the ground connection 29,and the back to back rectifying diodes 35 and 36 are provided as beforethat connect to output terminal 37 and rail 17. A current adequate tohold the coil 72 operative, but inadequate to operate the motor, isprovided by a holding cir cuit including the resistor 73 and a normallyclosed switch 74, together paralleling the potentiometer resistor 31 andits slider 33. Thus, if the slider 33 is moved to stop or open circuitposition, the current on the positive half of the A.C. cyclenevertheless passes to the rail 17 via the holding circuit. This currentis adequate to overpower the spring 71. However, by opening the switch74, when the slider 33 is at a stopped position, the holding current forthe latching relay 72 is interrupted, and the spring 71 reverses themotor field.

A similar holding circuit is provided for the opposite or negative halfcycle of the supply for use in controlling the latching relay 70 for theother locomotive. Thus, the holding circuit includes the holdingresistance 73 and the normally closed switch 74', together parallelingthe potentiometer resistor 32 and its slider 34.

In order to improve voltage regulation under varied load conditions, thearrangement of FIG. 3 may be provided. In this example, two batteries 81and 82 are provided in place of power transformer 26. The batteries havea plurality of series connected cells and voltage taps therebetween,whereby sliders or selector switch arms 83 and 84 may be moved todifferent voltage positions.

The taps 83 and 84 connect with opposite contacts 85 and 86 of a chopperstructure. Thus, an arm 87, vibrated by an A.C. coil 88, alternatelyengages the contact 85 and 86 to provide an alternating current, thepositive and negative halves of which are separately controlled by taps83 and 84.

The chopper connects with a reversing circuit 89, which in turn connectsto the track rails.

In FIG. 4, still another power supply system provides improvedregulation. In the present instance, unidirectionally conductive devices91 and 92 in the form of controlled rectifiers are utilized.

The rectifier 91 has a cathode 93 connected to a slider 94 thatcooperates with a secondary Winding 95 of a power transformer 96. Thecontrolled rectifier 92 has its anode 97 connected by a lead 98 to aslider 99 cooperable with a secondary winding 100 of a second powertransformer 101. The controlled rectifiers 91 and 92 thus provideconduction for the positive and negative halves of the A.C. wave, andthe taps 94 and 99 separately control amplitude.

The anode 102 of the rectifier 91 and the cathode 103 of the rectifier92 are connected together as at 104 to form a common output terminal forthe power supply as in the previous forms.

The low internal impedance of the transformers 96 and 101 ensures goodvoltage regulation for the locomotives connected to the track rails 17and 18.

In order to prevent a short circuit between the transformer secondarywindings 94 and 99 via devices 91 and 92, the gates 105 and 106 of therectifiers are controlled by circuits 107 and 108. These circuits limitconduction to the corresponding half cycles. The control circuits may beof any suitable design deriving excitation from the transformersecondary windings.

A reversing circuit is interposed between the output terminal 94 andtrack rails to provide separate direction control.

In the form illustrated in FIG. 5, controlled rectifiers 111 and 112 areconnected in back-to-back relationship. Thus, the anode 113 of therectifier 111 and the cathode 114 of the rectifier 112 are connected tothe common terminal 115, which by lead 116 connects one terminal 117 ofthe transformer secondary winding 118. The other terminal of the winding118 is grounded, as at 119. The cathode 120 of the device and the anode121 of the rectifier 112 are connected together at a common outputterminal122.

Cooperable with gate 123 and 124 of the respective rectifiers 111 and112 are control circuits 125 and 126 used to control the ratio ofon-time to oif-time whereby energy applied during opposite halves of theA.C. wave form.

In the form illustrated in FIG. 7, locomotives 210 and 211 areillustrated that each cooperate with track conductors 212 and 213. Apower supply 214 and reversing circuits shown in block diagram may bethe same as illustrated for the form shown in FIG. 1.

The locomotive 210 has a reversible motor 21.5, a

rectifying diode 216, a coil 217 of a reversing relay 218, all similarto the arrangement of FIG. 1. However, serially associated with therelay coil is a device 219 having the characteristic that it conductsonly on the application of a critical voltage. This critical voltage bydesign exceeds any voltage applied to the coil 217 during normal runningconditions, but is less than the voltage that can be applied to the coil217 by the reversing circuits, and via diode 216. Accordingly, until apulse is applied for operating the relay coil 217, no current ispermitted to pass to it, and chattering is avoided. This is especiallyimportant since the locomotive may be subject to vibrations and the likethat might, coupled with chattering of the relay, produce spuriousoperation.

The device 219 may be a four layer Shockley diode, a Zener diode, or anyother device, not necessarily unidirectionally conductive, having thedesired critical voltage characteristic.

A similar device 220 is provided for the companion locomotive 211, andsince the device 220 is unidirectionally conductive, its polarity isreversed to conform to the desired direction of current flow.

The inventor claims:

1. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and in response to a polarized signaltransmitted via the corresponding unidirectionally conductive element;and means for separately supplying signals to said conductors ofopposite polarities respectively to operate the corresponding reversingrelay.

2. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and dependent upon the correspondingunidirectionally conductive element, each relay being operative inresponse to a current pulse; means for applying current pulses ofopposite polarities to the said conductors for separately reversing saidmotor.

3. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and dependent upon the correspondingunidirectionally conductive element, each relay being operative inresponse to an interruption of current; means normally maintainingholding currents of both polarities for the respective. relays; andmeans for selectively interrupting the said holding currents forseparately reversing said motors.

4. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and dependent upon the correspondingunidirectionally conductive element, each relay being operativeinresponse to a current pulse; a pair of capacitors;

6 switch means for each capacitor and movable to first positions forapplying the charge thereof across said conductors, and movable tosecond positions in which said capacitors are isolated from saidconductors; and means operative upon movement of said switches to saidsecond positions for oppositely charging said capacitors.

5. The combination as set forth in claim 4, together with meansproviding an alternating current the opposite phases of which areseparately controlled; and means applying said alternating current tosaid conductors and dependent upon both said switches being in theirsaid first positions.

6. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and dependent upon the correspondingunidirectionally conductive element, each relay being operative inresponse to an interruption of current; first means including aunidirectionally conductive device and a variable impedance for passingcurrent in one direction to said conductors; second means including aunidirectionally conductive device and a variable impedance for passingcurrent in the other direction to said conductors; circuit meansparallelling one of said variable impedances to maintain a minimumaverage current in one direction; circuit means paralleling the other ofsaid variable impedances to maintain a minimum average current in theother direction; each of said circuit means including a make-and-breakswitch for separately reversing said motors.

7. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each of said motors having a pair of field windingsrespectively operable to turn the corresponding motor in oppositedirections; each power unit including a relay dependent upon thecorresponding unidirectionally conductive element and of the type thatmoves to contact stations successively upon the application ofsuccessive pulses; circuit means, completed by each relay foralternately connecting the corresponding field windings; and means forseparately applying pulses of opposite polarities respectively tooperate the corresponding relays.

8. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor connecting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely polarized; a pair of batteries having terminals of oppositepolarities connected to one of said conductors, each battery having aseries of taps between cells thereof whereby voltages of various valuescan be derived therefrom; a movable arm for each battery; and choppermeans for alternately connecting the arms to the other of saidconductors.

9. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor connecting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely polarized; a pair of batteries having terminals of oppositepolarities connected to one of said conductors, each battery having aseries of taps between cells thereof whereby voltages of various valuescan be derived therefrom; a movable arm for each battery; chopper meansfor alternately connecting the arms to the other of said conductors;each power unit further including a relay dependent upon thecorresponding unidirectionally conductive element and of the type thatmoves to contact stations successively upon the application ofsuccessive pulses of magnitude larger than provided by any tap of saidbatteries; circuit means completed by each relay for reversing thecorresponding motor; and means interposed between the chopper means andthe said other conductor for selectively applying pulses of oppositepolarities to said other conductor to reverse the corresponding motors.

16. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor connecting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely polarized; a pair of transformer windings excited from acommon source; each winding having sliders operable to derive voltagesof various values therefrom; corresponding terminals of said windingsbeing connected to one of said conductors; a first controlled rectifierhaving its anode connected to the other terminal of one of saidwindings; a second controlled rectifier having its cathode connected tothe other terminal of the other of said windings; the cathode of thefirst rectifier and the anode of the second rectifier being connected tothe other of said conductors; and control circuits for the respectiverectifiers limiting conduction to alternate half cycles of the source.

11. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor connecting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely polarized; a pair of transformer windings excited from acommon source; each winding having sliders operable to derive voltagesof various values therefrom; corresponding terminals of said windingsbeing connected to one of said conductors; a first controlled rectifierhaving its anode connected to the other terminal of one of saidwindings; a second controlled rectifier having its cathode connected tothe other terminal of the other of said windings; the cathode of thefirst rectifier and the anode of the second rectifier being connected tothe other of said conductors; control circuits for the respectiverectifiers limiting conduction to alternate half cycles of the source;each power unit further including a relay dependent upon thecorresponding unidirectionally conductive element and of the type thatmoves to contact stations successively upon the application ofsuccessive pulses of magnitude larger than provided by windings; circuitmeans completed by each relay for reversing the corresponding motor; andmeans interposed between the rectifiers and the said other conductor forselectively applying pulses of opposite polarities to said otherconductor to reverse the corresponding motors.

12. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor connecting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely polarized; a pair of controlled rectifiers connected inbackto-back relationship, the anode of one of the rectifiers and thecathode of the other of the rectifiers being connected to one of saidconductors; means applying alternating current excitation between theother of said conductors and the cathode of said one rectifier andbetween the other of said conductors and the anode of said otherrectifier; and means separately controlling the phase angle at whichsaid rectifiers are rendered conductive.

13. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor connecting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely polarized; a pair of controlled rectifiers connectedback-toback relationship, the anode of one of the rectifiers and thecathode of the other of the rectifiers being connected to one of saidconductors; means applying alternating current excitation between theother of said conductors and the cathode of said one rectifier andbetween the other of said conductors and the anode of said otherrectifier; means separately controlling the phase angle at which saidrectifiers are rendered conductive; each power unit further including arelay dependent upon the corresponding unidirectionally conductiveelement and of the type that moves to contact stations successively uponthe application of successive pulses of magnitude larger than providedby alternating current excitation applying means; circuit meanscompleted by each relay for reversing the corresponding motor; and meansinterposed between the rectifiers and the said other conductor forselectively applying pulses of opposite polarities to said otherconductor to reverse the corresponding motors.

14. In a control system for a pair of vehicles both deriving energy froma common pair of conductors; a pair of power units for the vehiclehaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and in response to a polarized signaltransmitted via the corresponding unidirectionally conductive element;means for separately applying signals to said conductors of oppositepolarities respectively to operate the corresponding reversing relay;each of said relays having a core; and means serially associated withthe coils for discriminating against the alternating current source forblocking the pulsations thereof from said relay coil While passing thereversing signals, as determined by the corresponding undirectionallyconductive elements.

15. In a control system for a pair of vehicles both deriving energy froma common pair of conductors; a pair of power units for the vehicles haveoppositely polarized unidirectionally conductive elements whereby theunits derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and only in response to a relatively highamplitude polarized pulse transmitted via the correspondingunidirectionally conductive element; each relay having a coil; and meansfor applying pulses of selected polarity for operating the correspondingreversing relays.

16. In a control system for a pair of vehicles both -rectifying diode216, a coil 217 of a reversing relay 218, all similar to the arrangementof FIG. 1. However, serially associated with the relay coil is a device219 having the characteristic that it conducts only on the applicationof a critical voltage. This critical voltage by design exceeds anyvoltage applied to the coil 217 during normal running conditions, but isless than the voltage that can be applied to the coil 217 by thereversing circuits, and via diode 216. Accordingly, until a pulse isapplied for operating the relay coil 217, no current is permitted topass to it, and chattering is avoided. This is especially importantsince the locomotive may be subject to vibrations and the like thatmight, coupled with chattering of the relay, produce spurious operation.

The device 219 may be a four layer Shockley diode, a Zener diode, or anyother device, not necessarily unidirectionally conductive, having thedesired critical voltage characteristic.

A similar device 220 is provided for the companion locomotive 211, andsince the device 220 is unidirectionally conductive, its polarity isreversed to conform to the desired direction of current flow.

The inventor claims:

1. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and in response to a polarized signaltransmitted via the corresponding unidirectionally conductive element;and means for separately supplying signals to said conductors ofopposite polarities respectively to operate the corresponding reversingrelay.

2. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and dependent upon the correspondingunidirectionally conductive element, each relay being operative inresponse to a current pulse; means for applying current pulses ofopposite polarities to the said conductors for separately reversing saidmotor.

3. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and dependent upon the correspondingunidirectionally conductive element, each relay being operative inresponse to an interruption of current; means normally maintainingholding currents of both polarities for the respective relays; and meansfor selectively interrupting the said holding currents for separatelyreversing said motors.

4. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and dependent upon the correspondingunidirectionally conductive element, each relay being operative inresponse to a current pulse; a pair of capacitors;

6 switch means for each capacitor and movable to first positions forapplying the charge thereof across said conductors, and movable tosecond positions in which said capacitors are isolated from saidconductors; and means operative upon movement of said switches to saidsecond positions for oppositely charging said capacitors.

5. The combination as set forth in claim 4, together with meansproviding an alternating current the opposite phases of which areseparately controlled; and means applying said alternating current tosaid conductors and dependent upon both said switches being in theirsaid first positions.

6. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit in cluding a relay operative toreverse the motor connections and dependent upon the correspondingunidirectionally conductive element, each relay being operative inresponse to an interruption of current; first means including aunidirectionally conductive device and a variable impedance for passingcurrent in one direction to said conductors; second means including aunidirectionally conductive device and a variable impedance for passingcurrent in the other direction to said conductors; circuit meansparallelling one of said variable impedances to maintain a minimumaverage current in one direction; circuit means paralleling the other ofsaid variable impedances to maintain a minimum average current in theother direction; each of said circuit means including a make-and-breakswitch for separately reversing said motors.

7. In a control system for a pair of vehicles both deriving energy froma common pair of conductors: a pair of power units for the vehicleshaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each of said motors having a pair of field windingsrespectively operable to turn the corresponding motor in oppositedirections; each power unit including a relay dependent upon thecorresponding unidirectionally conductive element and of the type thatmoves to contact stations successively upon the application ofsuccessive pulses; circuit means, completed by each relay foralternately connecting the corresponding field windings; and means forseparately applying pulses of opposite polarities respectively tooperate t-he corresponding relays.

8. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor connecting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely .polarized; a .pair of batteries having terminals of oppositepolarities connected to one of said conductors, each battery having aseries of taps between cells thereof whereby voltages of various valuescan be derived therefrom; a movable arm for each battery; and choppermeans for alternately connecting the arms to the other of saidconductors.

9. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor connecting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely polarized; a pair of batteries having terminals of oppositepolarities connected to one of said conductors, each battery having aseries of taps between cells thereof whereby voltages of various valuescan be derived therefrom; a movable arm for each battery; chopper meansfor alternately connecting the arms to the other of said conductors;each power unit further including a relay dependent upon thecorresponding unidirectionally conductive element and of the type thatmoves to contact stations successively upon the application ofsuccessive pulses of magnitude larger than provided by any tap of saidbatteries; circuit means completed by each relay for reversing thecorresponding motor; and means interposed between the chopper means andthe said other conductor for selectively applying pulses of oppositepolarities to said other conductor to reverse the corresponding motors.

10. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor connecting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely polarized; a pair of transformer windings excited from acommon source; each winding having sliders operable to derive voltagesof various values therefrom; corresponding terminals of said windingsbeing connected to one of said conductors; a first controlled rectifierhaving its anode connected to the other terminal of one of saidwindings; a second controlled rectifier having its cathode connected tothe other terminal of the other of said windings; the cathode of thefirst rectifier and the anode of the second rectifier being connected tothe other of said conductors; and control circuits for the respectiverectifiers limiting conduction to alternate half cycles of the source.

11. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor connecting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely polarized; a pair of transformer windings excited from acommon source; each winding having sliders operable to derive voltagesof various values therefrom; corresponding terminals of said windingsbeing connected to one of said conductors; a first controlled rectifierhaving its anode connected to the other terminal of one of saidwindings; a second controlled rectifier having its cathode connected tothe other terminal of the other of said windings; the cathode of thefirst rectifier and the anode of the second rectifier being connected tothe other of said conductors; control circuits for the respectiverectifiers limiting conduction to alternate half cycles of the source;each power unit further including a relay dependent upon thecorresponding unidirectionally conductive element and of the type thatmoves to contact stations successively upon the application ofsuccessive pulses of magnitude larger than provided by windings; circuitmeans completed by each relay for reversing the corresponding motor; andmeans interposed between the rectifiers and the said other conductor forselectively applying pulses of opposite polarities to said otherconductor to reverse the corresponding motors.

12. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor con necting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely polarized; a pair of controlled rectifiers connected inbackto-back relationship, the anode of one of the rectifiers and thecathode of the other of the rectifiers being connected to one of saidconductors; means applying alternating current excitation between theother of said conductors and the cathode of said one rectifier andbetween the other of said conductors and the anode of said otherrectifier; and means separately controlling the phase angle at whichsaid rectifiers are rendered conductive.

13. In a control system for a pair of toy or model locomotives: a tracksystem including a pair of conductors; a first locomotive power unithaving pickup means cooperable with the conductors to derive energytherefrom; a motor for each power unit; circuit means including aunidirectionally conductive element for each motor connecting the motoracross the pickup means for deriving energy from said conductors, theunidirectionally conductive means for the respective motors beingoppositely polarized; a pair of controlled rectifiers connectedback-toback relationship, the anode of one of the rectifiers and thecathode of the other of the rectifiers being connected to one of saidconductors; means applying alternating current excitation between theother of said conductors and the cathode of said one rectifier andbetween the other of said conductors and the anode of said otherrectifier; means separately controlling the phase angle at which saidrectifiers are rendered conductive; each power unit further including arelay dependent upon the corresponding unidirectionally conductiveelement and of the type that moves to contact stations successively uponthe application of successive pulses of magnitude larger than providedby alternating current excitation applying means; circuit meanscompleted by each relay for reversing the corresponding motor; and meansinterposed between the rectifiers and the said other conductor forselectively applying pulses of opposite polarities to said otherconductor to reverse the corresponding motors.

14. In a control system for a pair of vehicles both deriving energy froma common pair of conductors; a pair of power units for the vehiclehaving oppositely polarized unidirectionally conductive elements wherebythe units derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections andin response to a polarized signaltransmitted via the corresponding unidirectionally conductive element;means for separately applying signals to said conductors of oppositepolarities respectively to operate the corresponding reversing relay;each of said relays having a core; and means serially associated withthe coils for discriminating against the alternating current source forblocking the pulsations thereof from said relay coil while passing thereversing signals, as determined by the corresponding undirectionallyconductive elements.

15. In a control system for a pair of vehicles both deriving energy froma common pair of conductors; a pair of power units for the vehicles haveoppositely polarized unidirectionally conductive elements whereby theunits derive excitation from opposite half cycles of an alternatingcurrent source applied to said conductors; said power units eachincluding a motor; each power unit including a relay operative toreverse the motor connections and only in response to a relatively highamplitude polarized pulse transmitted via the correspondingunidirectionally conductive element; each relay having a coil; and meansfor applying pulses of selected polarity for operating the correspondingreversing relays.

16. In a control system for a pair of vehicles both deriving energy froma common pair of conductors; a pair of power units for the vehicleshaving oppositely polarized uni'directionally conductive elementswhereby the units derive excitation from opposite half cycles of analternating current source applied to said conductors; said power unitseach including a motor; each power unit including a relay operative toreverse the motor connections and only in response to a relatively highamplitude polarized pulse transmitted via the correspondingunidirectionally conductive element; each relay having a coil; means forapplying pulses of selected polarity for obtaining the correspondingreversing relays; and a device serially associated with each relay coilfor permitting conduction only upon the application of a criticalvoltage for preventing chattering of the relays.

References Cited by the Examiner UNITED STATES PATENTS ARTHUR L. LAPOINT, Primary Examiner. LEO QUACKENBUSH, EUGENE G. BOTZ, Examiners.

1. A CONTROL SYSTEM FOR A PAIR OF VEHICLES BOTH DERIVING ENERGY FROM ACOMMON PAIR OF CONDUCTORS: A PAIR OF POWER UNITS FOR THE VEHICLES HAVINGOPPOSITELY POLARIZED UNIDIRECTIONALLY CONDUCTIVE ELEMENTS WHEREBY THEUNITS DERIVE EXCITATION FROM OPPOSITE HALF CYCLES OF AN ALTERNATINGCURRENT SOURCE APPLIED TO SAID CONDUCTORS; SAID POWER UNITS EACHINCLUDING A MOTOR; EACH POWER UNIT INCLUDING A RELAY OPERATIVE TOREVERSE THE MOTOR CONNECTIONS AND IN RESPONSE TO A POLARIZED SIGNALTRANSMITTED VIA THE CORRESPONDING UNIDIRECTIONALLY CONDUCTIVE ELEMENT;AND MEANS FOR SEPARATELY SUPPLYING SIGNALS TO SAID CONDUCTORS OFOPPOSITE POLARITIES RESPECTIVELY TO OPERATE THE CORRESPONDING REVERSINGRELAY.